What do you fight Wordpress Spam Registrations With?
I only give admin accounts the ability to create accounts. If someone wants to publish content, they need to fill out a contact form to send me an email. If I approve them, they will be given an account to use. That way I don't have to worry about spammers signing up to spam.
I run a Buddypress site so technically I'm bound to signups. I have been testing out Akismet and Invisible reCaptcha for Wordpress.